HP VPN Firewall Appliances VPN Configuration Guide

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Tunnel type Tunnel mode
Tunnel source/destination
address
Tunnel interface
address t
yp
e
Automatic tunnel
Automatic
IPv4-compatible IPv6
tunneling
The source IPv4 address is
manually configured. The
destination IPv6 address is
automatically obtained.
IPv4-compatible IPv6
address, in the format
of ::IPv4-source-addres
s/96
6to4 tunneling
The source IPv4 address is
manually configured. The
destination IPv4 address is
automatically obtained.
6to4 address, in the
format of
2002:IPv4-source-addr
ess::/48
Intra-site automatic tunnel
addressing protocol
(ISATAP) tunneling
The source IPv4 address is
manually configured. The
destination IP address is
automatically obtained.
ISATAP address, in the
format of
Prefix:0:5EFE:IPv4-sour
ce-address/64
1. IPv6 over IPv4 manual tunneling
An IPv6 over IPv4 manual tunnel is a point-to-point link and its source and destination IPv4
addresses are manually configured. You can establish an IPv6 over IPv4 manual tunnel to connect
isolated IPv6 networks over an IPv4 network, or connect an IPv6 network to an IPv4/IPv6
dual-stack host over an IPv4 network.
2. Automatic IPv4-compatible IPv6 tunneling
An automatic IPv4-compatible IPv6 tunnel is a point-to-multipoint link. Both ends of the tunnel use
IPv4-compatible IPv6 addresses. The address format is 0:0:0:0:0:0:a.b.c.d/96, where a.b.c.d is
the IPv4 address of the tunnel destination. This mechanism simplifies tunnel establishment.
Automatic IPv4-compatible IPv6 tunnels have limitations because IPv4-compatible IPv6 addresses
must use globally unique IPv4 addresses.
3. 6to4 tunneling
{ Ordinary 6to4 tunneling
A 6to4 tunnel is a point-to-multipoint automatic tunnel. It is built between border routers and is
used to connect multiple isolated IPv6 networks over an IPv4 network. The destination IPv4
address of a 6to4 tunnel is embedded in the destination 6to4 addresses of packets. This
mechanism enables the device to automatically get the tunnel destination address, simplifying
tunnel establishment.
The 6to4 address format is 2002:abcd:efgh:subnet number::interface ID/64, where 2002 is
the fixed IPv6 address prefix, and abcd:efgh represents a 32-bit globally unique IPv4 address
in hexadecimal notation. For example, 1.1.1.1 can be represented by 0101:0101. The IPv4
address identifies a 6to4 network (an IPv6 network where all hosts use 6to4 addresses). The
border router of a 6to4 network must have the IPv4 address abcd:efgh configured on the
interface connected to the IPv4 network. The subnet number identifies a subnet in the 6to4
network. The subnet number::interface ID uniquely identifies a host in the 6to4 network.
6to4 tunneling uses an IPv4 address to identify a 6to4 network. This method overcomes the
limitations of automatic IPv4-compatible IPv6 tunneling.
{ 6to4 relay
A 6to4 tunnel is only used to connect 6to4 networks using IP prefix 2002::/16. IPv6 network
addresses such as 2001::/16 might also be used in IPv6 networks. To connect a 6to4 network
to an IPv6 network, a 6to4 router must be used as a gateway to forward packets to the IPv6
network. Such a router is called a 6to4 relay router.